In a manufacturing facility for automobiles, for example, machining robots for machining works, such as welding, are provided on both sides of each of machining stages located at a plurality of locations on a conveying passage. A work is mounted on a pallet, and a fixing jig for positioning and fixing the pallet is provided at each of the stages. The work is conveyed, together with the pallet, to a fixing jig by conveying means such as carrying robot, where the work is fixed by the fixing jig and machined by a machining robot in the fixed state. After the machining is completed at the stage, the work is conveyed by conveying means to a next stage for another process.
A robot for use not only in welding but also in carrying a work is disclosed in Japanese Laid-open Patent Publication No. 2001-138969. This robot is engaged in a guiderail provided along a conveying passage and movable along the guiderail. Two of such robots are positioned on each side of the conveying passage, adding up to four of these robots. These welding robots weld a work, and each of the robots supports the work and move along the guiderail, thereby carrying the work to a next stage for another process.
However, in the case of the robot disclosed in Japanese Laid-open Patent Publication No. 2001-138969, the guiderail serving as a traveling axis is required to be horizontally leveled with a high degree of accuracy.
Also, in the case of the robot supporting a work with a pallet, a dedicated pallet has been required for each kind of work, for example, for each type of motor vehicle. Furthermore, in order that a pallet used once is reused, the pallet has been required to be re-circulated in a machining process.